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Author Topic: High Resolution Scans  (Read 14727 times)
Dennis Vogel
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« on: July 14, 2008, 03:06:00 PM »
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I have some old photos that I'd like to archive in digital form.  I want to scan them at the highest resolution possible.  I have a Microtek ScanMaker 6100 which claims to have a 6400x3200 DPI CCD and the companion Scan Wizard software.  I know I don't need super high resolution to make decent prints but I feel like I should get as much resolution as possible for any potential future use.

I'm currently using Corel Paint Shop Pro X 10.03.  PSP reportedly has a limit of 32768 pixels per side for an image.  Some modest sized photos when scanned into TIFF files can easily exceed that even at less than the max the scanner can produce.  Turns out the 32768 max isn't even real.  There appears to be a total file size limit that is the real limit.  I have some photos that are less than 32768 pixels per side but PSP cannot load them.  Some of the files are about 500 MB.  I am running Windows XP and I have 2 GB of memory.  Even with most other applications shut down and 1.5 GB of free memory I still cannot get PSP to load the file.  I'm assuming it needs to load the entire image into memory and possibly keep some memory for undoing.

So, I'm looking for an image editing program that will handle very large images.  I will only need to do some basic operations such as cropping, cloning or other restoration techniques.  I guess I need either a very memory efficient app or one that somehow can manipulate images without needing to load the entire thing into memory, if there even is such a thing.  I don't particularly want to spring for Photoshop as I'm strictly an amateur and don't need the full power it offers.  Besides, I think I read or heard PS has limits similar to PSP for image sizes it will accept.  Any suggestions?

Dennis
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Plekto
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« Reply #1 on: July 14, 2008, 05:00:48 PM »
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Any scanner's actual optical resolution is going to be the lesser of the two numbers.  So 3200*3200 will produce essentially the same results - cleaner in fact, for archiving, since there's no software interpolation going on.

Half the file size.  win-win.  It might be small enough to open then...
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Dennis Vogel
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« Reply #2 on: July 14, 2008, 10:34:12 PM »
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Any scanner's actual optical resolution is going to be the lesser of the two numbers.  So 3200*3200 will produce essentially the same results - cleaner in fact, for archiving, since there's no software interpolation going on.

Half the file size.  win-win.  It might be small enough to open then...
[a href=\"index.php?act=findpost&pid=208197\"][{POST_SNAPBACK}][/a]
Thanks for the advice.  I'd like to try that.  But I can't come close to opening a 3200x3200 scan with PSP.  For one photo I'm testing with PSP will load an 1800x1800 scan but cannot load a 2000x2000.  So if I wanted to use 3200x3200 what app will handle images that size?

Dennis
« Last Edit: July 14, 2008, 11:27:05 PM by Dennis Vogel » Logged
BernardLanguillier
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« Reply #3 on: July 14, 2008, 11:08:21 PM »
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DPI isn't everything. The 2000 DPI scans I am getting from my old Imacon are sharper than the 4000 DPI scans I was getting from my Coolscan 9000. Besides the most important thing is DR, and specifically the ability to extract useful information from shadows. This is especially important for contrasty slide films like Velvia.

As far as large files go, PS CS3 can for sure handle them. I believe that the .psb file format has a limit of 300.000 pixels. I have never been above 50.000 pixels on the long end with a file in the 6GB range (multi-layers obviously).

Cheers,
Bernard
« Last Edit: July 14, 2008, 11:10:08 PM by BernardLanguillier » Logged

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Sheldon N
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« Reply #4 on: July 14, 2008, 11:11:39 PM »
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From your post it sounds like you are scanning photos, and not negatives. If that's the case, there is no need to scan at much higher than 300-400dpi. A photo has very limited detail, while a negative can contain very high resolution details that would warrant a 3200 dpi scan.

The human eye can't perceive more detail than ~300dpi in a print, even up close, so if you are not intending to enlarge and reprint the photos this would be sufficient to archive the image. I also doubt that there is much more useable resolution in the photo than 300-400dpi, the paper just won't hold that much detail.

Try a 300 dpi scan, a 500 dpi scan, and a 1000 dpi scan of the same small section of print. Compare them side by side on screen and see if there is really any useable resolution gained by going to higher dpi's. I would guess that there is not.

Hope this helps!
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Dennis Vogel
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« Reply #5 on: July 14, 2008, 11:29:14 PM »
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As far as large files go, PS CS3 can for sure handle them. I believe that the .psb file format has a limit of 300.000 pixels. I have never been above 50.000 pixels on the long end with a file in the 6GB range (multi-layers obviously).
Is that 300,000 pixels per side or 300,000 total?  I'm guessing it's per side because 300,000 total is only about 540x540 pixels.

Dennis
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Dennis Vogel
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« Reply #6 on: July 14, 2008, 11:34:38 PM »
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From your post it sounds like you are scanning photos, and not negatives. If that's the case, there is no need to scan at much higher than 300-400dpi. A photo has very limited detail, while a negative can contain very high resolution details that would warrant a 3200 dpi scan.
I wasn't really clear but I have photos, slides and some negatives.
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The human eye can't perceive more detail than ~300dpi in a print, even up close, so if you are not intending to enlarge and reprint the photos this would be sufficient to archive the image. I also doubt that there is much more useable resolution in the photo than 300-400dpi, the paper just won't hold that much detail.
OK, that's a figure I've not seen elsewhere.  I may want to print some in the future but who knows what new technology will come along in the future that can use more resolution.  I'd hate to think I threw away some resolution when that time comes.
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Try a 300 dpi scan, a 500 dpi scan, and a 1000 dpi scan of the same small section of print. Compare them side by side on screen and see if there is really any useable resolution gained by going to higher dpi's. I would guess that there is not.
That's a good idea.  I've been scanning some test photos but only at various high resolutions to see what the max PSP can handle.  But will the resolution of my monitor limit what I'm seeing?  In other words, could there be more resolution in a scan at, say 1000 dpi, that doesn't show up due to my monitor?

Dennis
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Sheldon N
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« Reply #7 on: July 15, 2008, 07:27:10 PM »
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But will the resolution of my monitor limit what I'm seeing?  In other words, could there be more resolution in a scan at, say 1000 dpi, that doesn't show up due to my monitor?

[a href=\"index.php?act=findpost&pid=208283\"][{POST_SNAPBACK}][/a]


If you view the scan at 100% pixel view, you are seeing everything that is there regardless of what dpi you scan at. Your monitor is roughly 72dpi, so think of the actual pixel monitor view as being roughly 4x larger than you'd print the photo.

More pixels does not equal more resolution. A print does not typically contain any more detail past a certain point, regardless of how finely you scan it. You just start to scan paper fibers and structure, not image detail.

A negative would be worth scanning at 3200 dpi. I would recommend 500dpi for a print scan.
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dalethorn
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« Reply #8 on: July 16, 2008, 12:05:50 PM »
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Even if PSP is not set for Undo's, it will require much more than 1 gb of RAM for a 500 mb image, and the available from your 2 gb is not enough.  PSP can swap to disk of course, but that's not doable with such a large image.  I've found that with some prints, I get much better results with 1200 or better DPI than with 600 or less.

BTW, my copy of PSP v6 is 12 years old, yet it will load anything that can fit into *available* RAM.
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Farkled
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« Reply #9 on: July 17, 2008, 07:21:58 PM »
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From my readings and experiences archiving my family's images, I'd say that prints have an upper limit of about 600dpi.  I would reserve that level for the very best prints and/or the astoundingly irreplaceable.  Among other reasons, I doubt you'll get a print to lay flat enough for a flatbed scanner to achieve an accurate focus at better than 600.  Today's printers printers don't achieve a 600 pixel density.

For negatives and positives, the literature suggest that anything past 4000 scans only noise.  With flatbeds there is also the focus issue.  I would scan iriginal size at 3200 (in your case) and save as JPG, reserving the TIF format for only the very best because of image size issues.

You'll have to decide how much processing to do when scanning as opposed to after the scan.
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BernardLanguillier
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« Reply #10 on: July 18, 2008, 02:51:15 AM »
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Is that 300,000 pixels per side or 300,000 total?  I'm guessing it's per side because 300,000 total is only about 540x540 pixels.
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Per side. First link found on a google search:

[a href=\"http://www.file-extensions.org/psb-file-extension-photoshop-s-large-document-format]http://www.file-extensions.org/psb-file-ex...document-format[/url]

Cheers,
Bernard
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Dennis Vogel
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« Reply #11 on: July 18, 2008, 03:01:55 PM »
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Per side. First link found on a google search:

http://www.file-extensions.org/psb-file-ex...document-format

Cheers,
Bernard
[a href=\"index.php?act=findpost&pid=209071\"][{POST_SNAPBACK}][/a]
That's very encouraging Bernard.  Do you happen to know if Photoshop Elements supports PSB or JPEG2000 files?  I can't see springing for the full PS package for my use.  I just don't need all that power for scanning and cropping my photos and slides.

Dennis
« Last Edit: July 18, 2008, 03:41:25 PM by Dennis Vogel » Logged
Dennis Vogel
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« Reply #12 on: July 18, 2008, 03:05:28 PM »
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Even if PSP is not set for Undo's, it will require much more than 1 gb of RAM for a 500 mb image, and the available from your 2 gb is not enough.  PSP can swap to disk of course, but that's not doable with such a large image.  I've found that with some prints, I get much better results with 1200 or better DPI than with 600 or less.
So, if Undo is turned off, why won't a 0.5 GB image load with 1.5 GB of memory available?  Do you know what it need all that memory for?

Dennis
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Plekto
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« Reply #13 on: July 18, 2008, 07:25:43 PM »
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You might try upping your swap file to something absurd like 10 gigs.  It should work, though it'll be astonishingly slow.
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dalethorn
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« Reply #14 on: July 18, 2008, 09:11:21 PM »
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So, if Undo is turned off, why won't a 0.5 GB image load with 1.5 GB of memory available?  Do you know what it need all that memory for?
Dennis
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You're assuming a one-to-one memory to file ratio.  First, the file is compressed.  Even ignoring that, PSP lays out a memory image much larger than the file size.  Thirdly, you really don't know how much of that memory Windows is allocating for cache (cache is automatic and dynamic), and when and if Windows will dump that cache for use by PSP.  You can get some low-level system tools to analyze that, or get more memory, or some additional software to pre-process that image to a better size.
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dalethorn
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« Reply #15 on: July 18, 2008, 09:15:44 PM »
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BTW, most prints above 4 x 6 inches probably don't have actual info beyond 600 DPI, but some small glossy prints do have info at 1200 DPI or better.  Anyone with scanning experience on a variety of "other people's" prints will encounter some of these, sooner or later.
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Dennis Vogel
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« Reply #16 on: July 18, 2008, 09:43:47 PM »
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You might try upping your swap file to something absurd like 10 gigs.  It should work, though it'll be astonishingly slow.
[a href=\"index.php?act=findpost&pid=209290\"][{POST_SNAPBACK}][/a]
10 gigs of swap for a 1/2 gig file!  Yow!  Why in the world would it need such an astronomical amount of swap space?  20 times the image size seems way out of bounds.  Can you explain where you got that number?  Is it based on some understanding of PSP's memory management algorithms or perhaps empirical results of experiments?

Dennis
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dalethorn
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« Reply #17 on: July 18, 2008, 10:04:25 PM »
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10 gigs of swap for a 1/2 gig file!  Yow!  Why in the world would it need such an astronomical amount of swap space?  20 times the image size seems way out of bounds.  Can you explain where you got that number?  Is it based on some understanding of PSP's memory management algorithms or perhaps empirical results of experiments?
Dennis
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PSP may allocate 20x memory for a small file, due to their overhead, but the ratio decreases for larger files.
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Dennis Vogel
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« Reply #18 on: July 19, 2008, 11:50:19 AM »
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PSP may allocate 20x memory for a small file, due to their overhead, but the ratio decreases for larger files.
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20x?  Whatever for?  Seems like sloppy memory management to me.

Dennis
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dalethorn
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« Reply #19 on: July 19, 2008, 12:13:57 PM »
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20x?  Whatever for?  Seems like sloppy memory management to me.
Dennis
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No, not sloppy at all.  I've been using PSP6 for 11+ years, without a glitch, which is *much* better than I can say for other software users (read the posts here).  I don't try loading 500 mb scans, however.  BTW, I write software for a living, and have done pioneering work in PC software, and I believe PSP is an outstanding program.
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